The present disclosure relates generally to color digital image processing, and more particularly to an improved system and method for display rotation.
It is well known that different color spaces such as a red, green, blue (RGB) primary color model, may be used to represent, process and/or describe color. Similar to the RGB primary color model, YUV is a well known and widely used color model for describing color space (or color information) in terms of luminance (Y) component that is indicative of the brightness and chrominance (U and V) components that are indicative of the color. The human eye is less sensitive to color variations than to intensity variations. The YUV format allows the encoding of luminance (Y) information at full bandwidth/resolution and chrominance (UV) information at reduced bandwidth/resolution. The YUV format, which was originally developed for backward compatibility with black and white television, uses a matrixed combination of RGB to reduce the amount of information in the signal for conserving bandwidth.
Chroma sub-sampling, which is a well known sampling technique, generally refers to the use of lower resolution (fewer bits) for digitally sampling the chrominance (U and V) information in an image compared to the luminance (Y) information. The chroma sub-sampling is usually expressed as a three part ratio of the number of luminance (Y) samples, followed by the number of samples of the chrominance (U and V) components for each sampled area of the image. For example, a YUV 4:2:2 samples the two color-difference components (U and V) at half the sample rate of the brightness (Y) component, thereby utilizing less memory and less bandwidth compared to a YUV 4:4:4 sample.
Pixel data associated with a digital image may be typically stored in memory. The digital image may be retrieved from the memory and displayed as a two dimensional display on an image output device, such as a display device, a printer device and similar others. The display device may include a liquid crystal display (LCD), a plasma display, a television (TV), a projector display and similar others. A user viewing the display may desire to rotate the display for optimized viewing, e.g., change from a portrait display orientation to a landscape display orientation. Traditional techniques for rotating the display may include use of software, which may be slow in terms of desired performance. Some techniques may use additional main memory as a temporary memory area for copying the image data into the temporary memory and then manipulating the copied image data for rotation. However, such techniques may be less efficient and costly due to the need for performing additional reads and writes on the image data to perform the rotation.